Tucked away in a top-secret location, next to the PSA factory in the Aulnay-sous-Bois region, it comprises more than 400 vehicles in 6500 square meters of temperature-controlled warehouse. It’s not open to the public, but it is awesome, so we thought you’d appreciate a virtual sneak-around.

The place is absolutely staggering. Firstly, it’s massive. Secondly, all of the cars are absolutely immaculate. Thirdly, there’s literally every contribution the manufacturer made to the wheeled world in here, from the sublime to the Very French.

There’s the first car ever made by the eponymous Andre Citroen - a 1919 Type A - right up to the latest Tubik concept, and the most quintessentially absurd contraptions inbetween. It’s a potent place, this - looking across the ranks of cars you realise just how many contributions this oft-derided manufacturer’s made to motoring.

When you look at the density of innovation in this place, the phrase ‘ahead of its time’ is unavoidable. OK, so we’ve descended into cliché, but we didn’t start it. Citroen did.

There’s the Traction Avant, which is the first car with torsion beam suspension and monocoque construction, The DS, which has swiveling headlights that move with the steering wheel (modern carmakers are still touting this as a cutting-edge innovation), hydraulic self-leveling suspension, which remains a staple of luxury cars. It appeared on the DS back in 1955. The list goes on….

But enough frotting. There’s plenty of stupid stuff too - fancy an AX roadster with a calculator in the dashboard? Or the very 2CV (equipped with four-pot GS engine) used in James Bond: For Your Eyes Only?

Click forth, brave TopGear.commer, and discover the wonders within…

Is this the coolest steering wheel in the history of EVER? Probably. It belongs to a CX 25 GTi Turbo 2.

Bet you won’t see one of these on the street - it’s a 1970 M35 Prototype Coupe. Citroen supplied these rotary-engined coupes to “a select number of technical enthusiasts” then asked them to put 30,000 test kilometers on the clock ready for the car’s launch in 1970. You can see “Prototype Citroen M35” in big black letters on the wing.

In 1976 a French artist called Jean-Pierre Lihou daubed on a GS X2 and called it the “Energetique”. There’s 73 different colors on here, all of which are combined with a module of arrows that are readable in two directions.

Apparently, it explores “the interpretation of dynamic concepts with evidence of forces that are the arrows and lines of tension.” Alrighty then.

This is Citroen’s contribution to Group B rallying; the four-wheel-drive BX 4TC. 200 road cars were built to meet homologation regulations, but it was so unsuccessful (its best result was sixth place in the 1986 Swedish rally) that it recalled and scrapped as many examples as it could.

In the seventies, Citroen cornered the henchman transportation market for the discerning lair owner.

This is a specially modified DS used to deliver the cash payments from HQ in Paris to Citroen workers at the factory in the suburbs. It got hijacked, so a special safe was built in the boot.

Didn’t believe us about the AX Roadster concept with a calculator in the dash? It’s called the Xanthia. Check out the double chevron tyre imprint.

Any rally cars, you ask?

This is the closest we’re willing to get to Roger Moore’s buttocks - the 2CV used in James Bond: For Your Eyes only. It was heavily modified for the driving scenes - Albert Broccoli had a roll cage, skid pan and four-pot GS engine fitted for its stunts, which took place on the island of Corfu.

A very tidy, very early Traction Avant - this is the first car built using monocoque construction. It was front-wheel drive, too. And a favourite of the French Resistance.

These are the original three 2CV concepts. The project began in 1936, destined for launch three years later at the ‘39 Paris motor show. Trouble was, France was occupied by the Nazis, so Citroen hid them in the attic of a farm building at the company’s test centre in Normandy in case they were destroyed.

They were unearthed in the nineties - one was restored and the other two preserved in as-found condition.

This is coolest Citroen…. In the world. Fact. It was used to test tyres in preparation for the SM’s launch.

Anyone for a prototype four-wheel-drive Visa with a 2.2-litre 210bhp engine in the middle?

If you listen carefully, you can here the gentle fizz of steel oxidizing.

This presidential limo was built by coachbuilders Chapron - them that made a convertible DS - and it’s 6.3 meters long. That made it bigger than the state cars used by Lyndon B Johnson and Richard Nixon. Not that presidents are into priapic displays of power or anything…

Remember the Tubik concept - the nine-seater concept van that appeared at last year’s Frankfurt motor show? This is where it lives. Read more about it here

These are the ZX Rallye Raid Evolution 2s Citroen took to the inaugural World Cup for Cross Country Rallying. Lartigue/Périn brought back the Driver’s and Constructor’s title in ‘93.

And here’s another, dwarfing some slightly more humble machinery.

These are the original models from the design studios. Citroen was an early pioneer of aerodynamics - it started using wind tunnels back in the fifties, and its CX was so slippery that it took its name from the term used to measure drag coefficient. Which is, unsurprisingly, Cx.

Here’s that bonkers AX Roadster thing again, sat next to some other state-of-the-eighties design studies.

Wondered where concepts go after motor shows? If they’re the Citroen Hypnos, right here.

A propos of nothing, here’s half a DS.

Citroen had a go at making helicopters. Hydropneumatic suspension is disappointingly absent.

The Maserati V6-powered SM was a handy rallyist, but not just because of its engine. The self-leveling suspension means it keeps its aerodynamic profile and instantly reacts to imperfections in the road surface.

The brakes run off the same hydraulic system, and you slow it down by pressing a weird zero-travel mushroom button on the floor - depending on the intensity of your foot pressure, a specific amount of fluid is fed to the brakes, so drivers can meter it perfectly. The front discs are also mounted inboard so there’s always true centre-line steering. Snazzy.

And finally, this is where the Citroen double chevron logo comes from - the company used to manufacture gears like this.

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